Re: [RFC v4 6/7] sprintf: Add [V]SPRINTF_END()

[Alejandro Colomar <alx@kernel.org>]

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Hi Linus,

On Thu, Jul 10, 2025 at 08:30:59PM +0200, Alejandro Colomar wrote:
> > IOW, why isn't this just
> > 
> >   #define sprintf_array(a,...) snprintf(a, ARRAY_SIZE(a), __VA_ARGS__)
> 
> Agree.  This is a better name for the kernel.

Oops, I misread.  I thought you were implementing it as

	#define sprintf_array(a, ...)  sprintf_end(a, ENDOF(a), __VA_ARGS__)

So, I prefer my implementation because it returns NULL on truncation.
Compare usage:

	if (linus_sprintf_array(a, "foo") >= ARRAY_SIZE(a))
		goto fail;

	if (alex_sprintf_array(a, "foo") == NULL)
		goto fail;

Another approach would be to have

	if (third_sprintf_array(a, "foo") < 0)  // -E2BIG
		goto fail;

Which was my first approach, but since we have sprintf_end(), let's just
reuse it.


Cheers,
Alex

-- 
<https://www.alejandro-colomar.es/>

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